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Mashing completes the breakdown of proteins and starches that began during the malting process. It is basically the steeping of grains in hot water. Three main styles of mashing include single-step infusion, step-infusion, and decoction. There are several advantages and disadvantages to each style. Along with the different styles, there are several different temperature ranges in which various reactions occur, these temperatures typically are taken advantage of during the step-infusion mashing process.

In a single-step infusion mash, malt is combined with hot water to reach a temperature appropriate for starch conversion. This temperature is right around 150° to 155° F. The mash is held at this temperature for the duration of the mashing process. A single-step infusion mash is easy to accomplish, requires a minimum amount of labor, equipment, energy, and time. It does not, however, allow the use of undermodified malts or adjuncts.

A step-infusion mash involves the mash to move through a series of temperature rests. The various temperature rests can be accomplished by an external heat source or by adding boiling water to raise the temperature. This style of mashing allows for more flexibility and use of undermodified malts and adjuncts. On the other hand, it requires more resources in the area of labor, energy (heat), and time. The various temperature ranges usually targeted by a step-infusion mash include:

Doughing-In: 95°-113° F for 20 minutes. (Not often used anymore, but has shown to improve total yield a couple of points.)

Protein Rest: 113°-131° F for 20-30 minutes. (Produces Free Amino Nitrogen and breaks up large proteins that form haze.)

Saccharification Rest (Starch Conversion): 150-155° F for 60 minutes. (Can be broken up into B-Amylase Rest 131°-150° F for 30-60 minutes and A-Amylase Rest 154°-162° F for 30-60 minutes. Compromise at 153° F for 60 minutes.)

A lower mash temperature (150° F or less) creates a thinner bodied, drier beer. A higher temperature (156° F) makes for a less fermentable, sweeter beer. These temperature variations allow for a brewer to really take control of their wort to produce a particular style of beer.

Decoction mashing involves removing a thick fraction of the mash and running it through a brief saccharification rest at a relatively high temperature. It is then boiled for 15-30 minutes before mixing it back into the main mash. This process can be repeated as much as 3 times and can be used to take you through the several temperature rests outlined above. A decoction mash improves extraction efficiency and promotes inelanoidin formation. This process is however the most resource intensive.

In general, most homebrewers use the single-step infusion mash, for obvious reasons. When creating a mash, a general rule of thumb is 1.25-1.5 quarts of water per 1 pound of grains. A mash containing 2 quarts or more of water pert pound of grain results in a thinner mash, which slows the conversion, but ultimately makes a more fermentable wort. A thicker mash, of less than 1.25 quarts of water per pound of grains, results in faster starch conversion, but creates a less fermentable wort and a sweeter, maltier beer. A thicker mash should be used for multirest mashes.

Cheers!